Brain functioning under acute hypothermic stress supported by dynamic monocarboxylate utilization and transport in ectothermic fish

Yung-Che Tseng, Sian Tai Liu, Marian Y. Hu, Ruo Dong Chen, Jay Ron Lee, Pung Pung Hwang*

*此作品的通信作者

研究成果: 雜誌貢獻期刊論文同行評審

13 引文 斯高帕斯(Scopus)

摘要

Background: The vertebrate brain is a highly energy consuming organ that requires continuous energy provision. Energy metabolism of ectothermic organisms is directly affected by environmental temperature changes and has been demonstrated to affect brain energy balance in fish. Fish were hypothesized to metabolize lactate as an additional energy substrate during acute exposure to energy demanding environmental abiotic fluctuations to support brain functionality. However, to date the pathways of lactate mobilization and transport in the fish brain are not well understood, and may represent a critical physiological feature in ectotherms during acclimation to low temperature.Results: We found depressed routine metabolic rates in zebrafish during acute exposure to hypothermic (18°C) conditions accompanied by decreased lactate concentrations in brain tissues. No changes in brain glucose content were observed. Acute cold stress increased protein concentrations of lactate dehydrogenase 1 (LDH1) and citrate synthase (CS) in brain by 1.8- and- 2.5-fold, paralleled by an increased pyruvate to acetyl-CoA transformation. To test the involvement of monocarboxylate transporters (MCTs) under acute cold stress in zebrafish, we cloned and sequenced seven MCT1-4 homologues in zebrafish. All drMCT1-4 are expressed in brain tissues and in response to cold stress drmct2a and drmct4a transcripts were up-regulated 5- and 3-fold, respectively. On the contrary, mRNA levels of drmct1a, -1b and -4b in zebrafish brain responded with a down regulation in response to cold stress. By expressing drMCTs in Xenopus oocytes we could provide functional evidence that hypothermic stress leads to a 2-fold increase in lactate transport in drMCT4b expressing oocytes. Lactate transport of other paralogues expressed in oocytes was unaffected, or even decreased during cold stress.Conclusion: The present work provides evidence that lactate utilization and transport pathways represent an important energy homeostatic feature to maintain vital functions of brain cells during acute cold stress in ectotherms.

原文英語
文章編號53
期刊Frontiers in Zoology
11
發行號1
DOIs
出版狀態已發佈 - 2014 八月 8

ASJC Scopus subject areas

  • 生態學、進化論、行為學與系統學
  • 動物科學與動物學

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